On 2/9/2018 7:51 PM, Felix Fietkau wrote:
This ensures that mac80211 allocated management frames are properly
aligned, which makes copying them more efficient.
For instance, mt76 uses iowrite32_copy to copy beacon frames to beacon
template memory on the chip.
Misaligned 32-bit accesses cause CPU exceptions on MIPS and should be
avoided.

Signed-off-by: Felix Fietkau <n...@nbd.name>
---
  include/net/mac80211.h | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 906e90223066..d999b8c8a44b 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -4149,7 +4149,7 @@ void ieee80211_sta_uapsd_trigger(struct ieee80211_sta 
*sta, u8 tid);
   * The TX headroom reserved by mac80211 for its own tx_status functions.
   * This is enough for the radiotap header.

Hi Felix,

Maybe useful to mention the alignment requirement in this comment block.

   */
-#define IEEE80211_TX_STATUS_HEADROOM   14
+#define IEEE80211_TX_STATUS_HEADROOM   16

Regards,
Arend

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